OLED display panel has gradually become one of the development trends in the flat-panel display field due to the advantages of low thickness, light weight, autoluminescence, wide viewing angle, high resolution, high brightness, rapid response, low energy consumption and the like.
A light-emitting device is disposed at a luminous region of each pixel unit in a pixel array of the OLED display panel, and each pixel unit is also provided with a thin-film transistor (TFT) disposed at a non-luminous region and configured to control the emission of the light-emitting device.
The light-emitting device takes an OLED device as an example. The method for manufacturing a TFT and an OLED in a pixel unit mainly comprises the following steps: preparing functional film layers of the TFT, e.g., a gate electrode, a gate insulating layer, an active layer and source/drain electrodes on a substrate in sequence at first; subsequently manufacturing a pixel electrode connected with the drain electrode; and finally preparing functional film layers of the OLED connected with the pixel electrode. Before the OLED is manufactured, a pixel defining layer (PDL) is prepared on the pixel electrode and configured to cover the TFT in the pixel unit and expose the region, used for manufacturing the OLED, in the pixel unit, so as to prevent film layer structures in the TFTs from being damaged by materials of the functional film layers in the OLED. The PDL is also configured to separate luminous regions (regions in which OLEDs are disposed) of different pixel units from each other.
Generally, the light-emitting device of each pixel unit may comprise a red light-emitting device for emitting red light, a green light-emitting device for emitting green light and a blue light-emitting device for emitting blue light. The OLED is disposed in the luminous region, defined by the PDL, in each pixel unit. Currently, the PDL generally adopts a single layer structure and is generally made of photoresist. A light-emitting layer of the OLED is generally made of a liquid organic light-emitting material by an inkjet printing technology. When the light-emitting layer of the OLED for emitting light of a certain color is prepared on the substrate, a liquid material ejected by the inkjet printing technology is prone to splash around. If the organic light-emitting material is splashed to luminous regions in which OLEDs of other colors have been disposed or splashed to luminous regions in which OLEDs of other colors to be formed are disposed, the light-emitting layers at the luminous regions will incur the problem of color blending, and hence the display effect can be seriously affected.
Moreover, as the PDL made of photoresist material is a hydrophobic organic material and the organic light-emitting material of the OLED is also a hydrophobic material, the contact area of the light-emitting layers formed by the inkjet printing technology with the PDL is large, and the light-emitting layer formed by the liquid organic light-emitting material in the luminous regions of the pixels are not smooth enough or may produce arched protrusions. Therefore, when a cathode is manufactured on the light-emitting layer, point contact can be easily incurred, and hence the problem of breakdown can be caused, and consequently the display effect can be seriously affected.